U.S. Army Space and Missile Defense Command

Evaluation of Cucumber and Melon Cultivars as Space Crop Candidates for Long-term Space Missions

Lillian F. Wang, LaShelle E. Spencer, Blake M. Costine, Aaron B. Curry et autres

Space crew members currently have access to limited options regarding fresh produce, highlighting the need for space crop production for long-term space missions. To expand the list of fresh crops that can be grown and consumed by crew members in space, cucumber …

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Third Harmonic Generation in Transparent Longitudinal Epsilon‐Near‐Zero Multilayers

Wallace Jaffray, Sven Stengel, Domenico de Ceglia, Neşet Aközbek et autres

ABSTRACT Epsilon‐near‐zero (ENZ) materials can dramatically enhance local optical fields, enabling nonlinear interactions at relatively low intensities. Yet, near their plasma frequency, isotropic ENZ media remain highly absorptive, limiting nonlinear operations that require good transparency. Longitudinal epsilon‐near‐zero (LENZ) metamaterials, characterized by a …

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Surprising cryptic cavefish diversity in a long-studied karst cave ecosystem of northern Alabama

Matthew L. Niemiller, Jonathan W. Armbruster, M W Sandel, Eric C. Maxwell et autres

Subterranean ecosystems host highly specialized and often cryptic biodiversity, yet even intensively studied landscapes may conceal deeply divergent vertebrate lineages. Here we describe Demogorgonichthys arcanus gen. et sp. nov., a new genus and species of cave-obligate fish discovered in Bobcat Cave, a …

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Why Participants Leave: A Qualitative Study Exploring Dropout from a Medication for Opioid Use Disorder (MOUD) Clinical Trial

Mercy Ngosa Mumba, Olayemi Timothy Adekeye, Fatima Akmal Leghari, Evans Kyei et autres

BACKGROUND: High dropout rates in clinical trials can undermine data validity, particularly among individuals with substance use and mental health disorders. This qualitative study examined reasons for participant dropout from a randomized trial evaluating the Minds and Mentors Program, a Mindfulness-Based Relapse …

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Active tracking coherent effects: speckle-induced noise-equivalent angle validation

Eric W. Mitchell, Mark F. Spencer, Wesley Barnes, Ronald G. Driggers

Active imaging systems leverage a coherent source to image distant targets and estimate target motion from reflected illumination. When a coherent source illuminates an optically rough surface, random amplitude fluctuations arise in the image (known as speckle), degrading overall tracking performance. A …

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Earth Global Reference Atmospheric Model (Earth-GRAM) 2026: User Guide

Patrick White

Reference or standard atmospheric models have long been used for design and mission planning of various aerospace systems. The NASA Global Reference Atmospheric Model (GRAM) was originally developed in response to the need for a design reference atmosphere that provides complete global …

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Integrating External Code in Simulink

David H Hosier

Since its founding, NASA has been dedicated to the advancement of aeronautics and space science.The NASA scientific and technical information (STI) program plays a key part in helping NASA maintain this important role.

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Impacts of Reduced Pressure Atmospheres on Environmental Control and Life Support Systems (ECLSS) Architectures

Morgan B. Abney, Robert M. Bagdigian, Chase Hopkins, Ariel V. Macatangay et autres

The study found that while nine subsystems are viable without modification at 10.2 psia, only three remain acceptable at 8.2 psia. Material flammability presents the most critical hurdle in the 8.2 psia/34-40% O2 environment, where 70% of the assessed subsystems will require …

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Modeling Study of Hatch Spacing’s Effect on Grain Morphology in Repairing Damaged Metal Parts with Welding and Hatch Spacing’s Potential Use in Lunar Exploration

Fredrick N Michael, Wei Li

The welding process is a potential way of repairing a damaged metal component, especially cavity damage caused by a harsh environment like the lunar environment, which is characterized by large temperature differences and reduced gravity. The adjustment of welding parameter (e.g., hatch …

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All-optical polarization control in time-varying low-index films via plasma symmetry breaking

Wallace Jaffray, Sven Stengel, Alexandra Boltasseva, Vladimir M. Shalaev et autres

Abstract Controlling the polarization state of light with sub-picosecond speed and sub-wavelength precision remains a key challenge for next-generation nanophotonic devices. Conventional methods, such as birefringent crystals, liquid crystals or electro-optic Pockels cells are limited in speed, compactness and energy consumption. While …

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Space Nuclear Propulsion for Space Applications: Multi-Mission Nuclear Thermal Propulsion Vehicle Design

Mitchell A. Rodriguez, Sarah A Triana, H Dan Thomas, Josh T Pastor et autres

This NASA Technical Memorandum (TM) is intended to capture design work that the Advanced Concepts Office (ACO) at NASA’s Marshall Space Flight Center (MSFC) performed on behalf of the Space Nuclear Propulsion (SNP) Project during an SNP-driven design and mission analysis initiative …

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Neuraxial anesthesia in obstetric patients with rare spinal pathologies: a scoping review

S. Reddi, S. Youssoffi, G. Papazyan, E. Papazyan et autres

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